Not sure if those keys are defined in the ini or not. There's a good chance they aren't...
Here is the Controls section of the Oblivion.ini I would say kyoma is correct, F1 - F4 are not defined in the .ini :nope:
Spoiler
[Controls]fVersion=1.8000Forward=0011FFFFBack=001FFFFFSlide Left=001EFFFFSlide Right=0020FFFFUse=00FF00FFActivate=0039FFFFBlock=003801FFCast=002EFFFFReady Item=0021FFFFCrouch/Sneak=001DFFFFRun=002AFFFFAlways Run=003AFFFFAuto Move=0010FFFFJump=0012FFFFToggle POV=001302FFMenu Mode=000FFFFFRest=0014FFFFQuick Menu=003BFFFFQuick1=0002FFFFQuick2=0003FFFFQuick3=0004FFFFQuick4=0005FFFFQuick5=0006FFFFQuick6=0007FFFFQuick7=0008FFFFQuick8=0009FFFFQuickSave=0044FFFFQuickLoad=0043FFFFGrab=002CFFFFbInvertYValues=0fXenonLookXYMult=0.0005fMouseSensitivity=0.0024;X = 1, Y = 2, Z = 3, XRot = 4, YRot = 5, ZRot = 6iJoystickMoveFrontBack=2iJoystickMoveLeftRight=1fJoystickMoveFBMult=1.0000fJoystickMoveLRMult=1.0000iJoystickLookUpDown=6iJoystickLookLeftRight=3fJoystickLookUDMult=0.0020fJoystickLookLRMult=0.0020fXenonMenuMousixYMult=0.0003bBackground Mouse=0bBackground Keyboard=0bUse Joystick=1fXenonLookMult=0.0030fXenonMenuStickSpeedMaxMod=5.0000iXenonMenuStickSpeedThreshold=20000iXenonMenuStickThreshold=1000;Language values: 0-English, 1-German, 2-French, 3-Spanish, 4-ItalianiLanguage=0SlideLeft=001EFFFFSlideRight=0020FFFFfXenonMenuStickMapCursorMinSpeed=1.0000fXenonMenuStickMapCursorMaxSpeed=15.0000fXenonMenuStickMapCursorGamma=0.1700fXenonMenuStickSpeedPlayerRotMod=3000.0000fXenonMenuDpadRepeatSpeed=300.0000fXenonMenuStickSpeed=300.0000iXenonMenuStickDeadZone=15000